HCM and PKD: cat health tests explained
What hypertrophic cardiomyopathy (HCM) and polycystic kidney disease (PKD) are, which breeds they affect, how breeders test for them and how to read the results.
By PurrTrust Editorial Team · Updated · 4 min read
When you ask a breeder about health testing, two abbreviations come up more than any others: HCM and PKD. Both are inherited diseases that can shorten a cat's life, and both can be screened for in the parents before a litter is planned. Understanding what the tests can and can't tell you helps you judge a breeder's answers.
What is HCM?
Hypertrophic cardiomyopathy (HCM) is a thickening of the heart muscle. It is the most commonly diagnosed heart disease in cats, in pedigree and non-pedigree cats alike. Many affected cats show no signs for years; in others it leads to heart failure, blood clots or sudden death. It can appear at any age, and often develops in adulthood rather than kittenhood.
HCM is a particular focus in the Maine Coon, Ragdoll, Sphynx and British Shorthair, and responsible breeders of many other breeds screen for it too.
How breeders test for HCM
There are two kinds of test, and they answer different questions.
- DNA tests look for one specific mutation. Two are in common use: the MyBPC3 A31P mutation in Maine Coons and the MyBPC3 R820W mutation in Ragdolls. A cheek swab is sent to a lab and the result never changes.
- An echocardiogram (heart ultrasound) looks at the heart itself and measures the muscle. It can detect HCM whatever the cause, but only shows the heart on the day of the scan, so breeding cats are usually re-scanned periodically, often yearly. Scans by a veterinary cardiologist are the most reliable.
The key point: a negative DNA test does not mean a cat can't develop HCM. It only rules out that one mutation. For breeds without a DNA test, echocardiograms are the only screening available, and for Maine Coons and Ragdolls the best breeders use both.
Reading HCM DNA results
- N/N (negative or clear): the cat has no copies of the mutation.
- N/HCM (heterozygous): one copy. The cat has a raised risk of developing HCM and can pass it on.
- HCM/HCM (homozygous): two copies. Risk is highest, and every kitten will inherit one copy.
Ask to see the lab report rather than a summary, and check that the cat's name or microchip on the report matches the parent you are being told about.
What is PKD?
Polycystic kidney disease (PKD) causes fluid-filled cysts to form in the kidneys. They are present from a young age and grow over time, and can eventually lead to kidney failure, usually in middle age. The common form is caused by a mutation in the PKD1 gene, which entered many lines through Persians.
PKD is most associated with the Persian and Exotic Shorthair, and with breeds that have had Persian outcrosses, such as the British Shorthair and Scottish Fold. Thanks to widespread testing it is much less common in tested lines than it once was.
How breeders test for PKD
- The PKD1 DNA test is simple and reliable for that mutation. Because PKD1 is dominant, any cat with even one copy is affected, so there are no healthy 'carriers'. Both parents should test negative.
- Kidney ultrasound by an experienced operator can find cysts. It was the main screening method before the DNA test and is still used in some situations, for example to look for forms of kidney disease the DNA test doesn't cover.
Recessive tests: carriers explained
Many other breed tests, such as SMA in Maine Coons or PK-def in Bengals and Abyssinians, are for recessive conditions. A carrier has one copy, is healthy, and can be bred safely to a clear cat; the risk comes when two carriers are bred together. So 'carrier' on a parent's report is not automatically a problem, as long as the other parent is clear.
What to ask a breeder
- Which health tests have both parents had, and can I see the reports?
- For HCM: when was each parent's most recent echocardiogram, and who performed it?
- For DNA tests: which lab did the test, and is the cat identified by microchip on the report?
- Have any related cats been diagnosed with HCM or kidney disease?
- Does the health guarantee cover HCM and PKD, and for how long?
Each breed guide lists the tests we recommend for that breed. On PurrTrust, breeders can upload parents' results, and litters show whether the core tests for the breed are verified.
After you bring your kitten home
Screened parents lower the risk but can't eliminate it. Tell your vet the breed and any family history, and ask whether a heart murmur or other signs warrant further checks. Routine wellness visits, including blood and urine tests as your cat ages, help catch kidney problems early.